Highly Regioselective Preparation of Heteroaryl–Magnesium Reagents by Using a Br/Mg Exchange

Disubstituted thienyl‐, furyl‐ and pyridylmagnesium derivatives are regioselectively prepared from a Br/Mg exchange of the corresponding dibromo compounds by using either iPrMgCl ? LiCl or hindered arylmagnesium reagents, such as isitylmagnesium bromide ? lithium chloride (isityl=2,4,6‐triisopropyl‐phenyl) complexed with a diamine ligand, in difficult cases. The selective functionalisations of these heterocyclic scaffolds by using Negishi cross‐coupling reactions, acylations or addition to aldehydes were readily achieved.